There seems to be an unwritten rule in modern US politics that former presidents generally stay out of politics, and in particular refrain from publicly criticizing the incumbent.
Former Vice President Dick Cheney, together with his daughter Liz Cheney, has just published a book entitled Exceptional, which appears to be mainly focused on condemning President Obama's foreign policy.
The New York Times comments in its review:
Former presidents may keep quiet about those who occupy the White House once they leave, but the code clearly does not extend to vice presidents.
Is there precedent for a former US vice president offering public criticism of a later administration?